bug(unic-archon-dlc): two Box nodes declare `runtime: bun` and nothing declares the dependency

Observed

unic-dlc-build.yaml:137 (slopcheck) and :596 (evidence) declare runtime: bun. On a fresh Linux VM with Archon 0.8.0 installed through the curl installer, the first run 3 build dispatch died 24 seconds in:

[slopcheck] Failed: Script node 'slopcheck' failed [exit ENOENT]: Executable not found in $PATH: "bun"

grep -rn '\bbun\b' docs/agents/ .archon/ -i in the Consumer hits only the two runtime: lines. Neither the plugin's docs nor docs/agents/unic-archon-dlc.md names bun. Runs 1 and 2 had it through Homebrew on macOS, probably as the Archon formula's dependency (unverified). Fixed for run 3 with mise use -g bun@1 → 1.4.2.

Why it matters

A Box that cannot start on a machine without an undeclared toolchain fails every Consumer on a new machine, and bootstrap's install_report: ok says nothing about it because the install command does not need bun.

Evidence

• Findings register, § "G. What run 3 taught about the instrument", row G2: https://github.com/unic/unic-agents-plugins/blob/bcf688a/docs/research/2026-08-31-dlc-run-2-findings.md
• Run record and harvested artefacts: ~/Desktop/run3-parked/ on the maintainer's machine (dispatch-log-c283e296.txt; run record § the first dispatch)
• Dispatch record: #457 from comment 5698289748 down

Not decided

• Whether the two script nodes should run on node (both import only node:* modules; untested on Archon 0.8.0) or bun stays and is declared.
• Where the declaration lives: /setup's install step, the Consumer doc's install section, or a bootstrap check that fails early with a named remedy.

Filed 2026-09-17 by wayfinder-orchestrator-10 from run 3's measurements. needs-specs: grill before dispatch.

Start with unic-dlc-build.yaml at lines 137 and 596, then read docs/agents/unic-archon-dlc.md and the /setup or bootstrap install path. Review the linked findings and dispatch record before deciding how the runtime dependency should be handled. Done means the choice is specified, documented, and a fresh Archon 0.8.0 Linux run can dispatch both nodes without an undeclared executable.